Transfer of [226]Ra and [137]Cs from tea leaves to drinking tea

Two of the important radionuclides which are entered to environment and human diet are radium-226 [[226]Ra] and cesium-137 [[137]Cs]. It is clear that the methods for preparation of foods such as peeling, washing, cooking or frying can affect the dose which is received by human due the to consumption of foodstuffs. An experiment has been performed at the environmental monitoring section of NRPD, aiming to measure the transfer of [226]Ra and [137]Cs from the tea leaves to drinking part of tea. Tea samples were pulverized to obtain a homogenous matrix which was weighed and placed in 1000 cm[3] Marinelli beaker. After making tea, the liquid tea and tea-discard were analyzed separately. Measurement of [226]Ra and [137]Cs was performed by gamma spectrometry system using a high purity germanium [HPGe] detector with 40 % relative efficiency. The detector was shielded by 10 cm lead an all sides with cadmium -copper as liners. It was found that the activity concentration transferred from tea leaves to drinking tea for [137]Cs and [226]Ra are less than 2% and 17% respectively. On the basis of these measurements it seems that no significant levels of radioactivity of [226]Ra and [137]Cs can be found in drinking part of tea. The low concentration of the mentioned radionuclides in drinking tea is mostly due to tea dust and can be removed by its washing before preparing tea

Derived intervention levels for mostly consumed foodstuffs in Iran

Measures to protect the public following an accidental release of radionuclides to the environment will depend on the circumstances including the extent of the potential hazards. The projected levels of risk are an important precondition in emergency planning. The levels can be expressed in terms of concentration levels in the environment or in foodstuffs. These derived intervention levels [DILs] can be determined for the range of important radionuclides that could be released to the environment in the event of a nuclear accident. Derived intervention levels for [90]Sr, [131]I, [134]Cs + [137]Cs, [238]Pu + [239]Pu + [241]Am and [103]Ru + [106]Ru radionuclide groups were calculated for infants [<1 year] and adults [>17 years] for mostly consumed foodstuffs in Iran. Calculations of DILs were based on recommendations from international, national organizations and average food consumption rate data for Iran. From our research it was found that DILs for foodstuffs consumed in Iran for above mentioned radionuclide groups except for Ruthenium group are equal to 387, 250, 1023 and 2.8 Bqkg[-1] respectively. The comparison of DILs for foodstuffs consumed in Iran and DILs adopted in the new food and drug administration [FDA] Compliance Policy Guide [CPG] which are 160, 170, 1200, 2 Bq.kg[-1] for [90]Sr, [131]I, [134/137]Cs, [238/239]Pu plus [241]Am radionuclide groups respectively, shows agreement with cesium and plutonium group and higher values for strontium and Iodine group. In the case of nuclear accident or radiological events that might affect our country calculated DILs can be used to prevent or reduce exposure due to consumption of foodstuffs

Gross beta activities and Beryllium-7 concentrations in surface air

Measurement of gross beta activities and cosmogenic Beryllium-7 concentrations were made each week during year 2002 from samples of atmospheric aerosols filtered from the air at Tehran Nuclear Research Center. The aerosol samples were collected weekly with high-volume air sampler at the Nuclear Research Center meteorological station in Tehran [40[degree sign] 35. N]. The [7]Be contents of samples were determined with semiconductor gamma spectrometry. The long-lived beta activity, i.e. total beta activity measured four days after the end of sampling [after decay of [220]Rn progeny and short-lived [220]Rn progeny], was assessed with an automatic beta analyzer. The long-lived beta activity consists mainly of [210]Bi, the daughter nuclide of [210]Pb, as the amount of artificial radionuclides in the air is negligible. The air concentrations of both the [7]Be and the long-lived beta activity displayed a lognormal distribution during the study period 2002. The arithmetic mean of annual concentrations of [7]Be and [210] Pb was 6.30 and 0.50 mBqm[-3], respectively. Despite the different origins, the concentrations of both the [7]Be and the long.lived beta activities are partially correlated. Both have maximum concentrations during warm mid-year months

Estimation of annual effctive dose from 226Ra and due to consumption of foodstuffs by inhabitants of Ramsar 228Ra city, Iran

[226]Ra and [228]Ra contents in foodstuffs of Ramsar which is a coastal city in the northern part of Iran were determined by gamma spectrometry. Measurement results together with food consumption rates were used to estimate annual effective dose from [226]Ra and [228]Ra, due to consumption of food stuffs by inhabitants of Ramsar city. A total of 33 samples from 11 different foodstuffs including root vegetables [beetroot], leafy vegetables [lettuce, parsley and spinach] and tea, meat, chicken, pea, broad bean, rice, and cheese were purchased from markets of Ramsar city and were analyzed for their [226]Ra and [228]Ra concentration. 1-8 kg of fresh weight sample was placed in Marinnelli beaker and sealed. The measurement of natural radioactivity levels as performed by gamma-spectrometry system, using a high purity germanium [HPGe] detector with 40% relative efficiency. The highest concentrations of [226]Ra and [228] Ra were determined in tea samples with 1570 and 1140 mBq/kg, respectively, and the lowest concentration of [226]Ra was in pea, cheese, chicken, broad bean, and beetroot.The maximum estimated annual effective dose from [226]Ra and [226]Ra due to consumption of foodstuffs were determined to be 19.22 and 0.71 microSv from rice and meat samples respectively, where as, the minimum estimated annual effective dose for [226]Ra was 0.017, 0.018 and 0.019 microSv from beetroot, cheese and pea samples respectively

Concentration of natural radionuclides in soil and assessment of external exposure to the public in Tehran

Natural radionuclides in soil constitute a significant component of the background exposure sources of the population. A meaningful contribution to the total dose from natural sources comes from terrestrial radionuclides such as 238U, 232Th and 40K. The concentrations of natural radionuclides of 238U, 232Th and 40K in surface soil [5 cm depth] of Tehran have been measured by gamma spectrometry. The samples were dried and homogenized and measured for 60k seconds after radionuclides secular equilibrium, using a high purity germanium [HPGe] gamma-ray spectrometer. The high energy resolution of this type of detector is particularly useful for activity measurements of uranium and thorium chain members due to their complex spectras. The absorbed dose rates in air were also measured by using ionization-chamber at the point where soil samples were collected which includes terrestrial and cosmic rays. The natural gamma emitting terrestrial radionuclides in soils are directly relevant to outdoor exposure. The average activity concentrations of 238U, 232Th and 40K in different districts of Tehran were found to be 24, 28 and 635 Bq kg-1, respectively. The average outdoor gamma absorbed dose rate in air at 1 meter above ground was calculated as 102 nGy h-1. By using the data obtained in this study the average annual effective dose equivalent for a person living in Tehran Sv. According to data of 66 soil samples was found to be about 125 measurement covering 22 districts in Tehran, the average outdoor gamma dose rate in air due to terrestrial and cosmic radiation was found to be about 102 nGy h-1 and the average annual effective dose equivalent for a person living in Tehran Svmicrois about 125